Stacked steampath and grooved bucket wheels for steam turbines
The steampath for a steam turbine includes stacked stator rings each mounting inwardly directed nozzles and stacked rotor wheels each mounting outwardly directed buckets mounting blades. By alternately stacking the stator rings and rotor wheels, the nozzles and buckets of the various stages are interdigitated to form a steampath. Each bucket includes a blade and a root received in a generally complementary shaped groove on a wheel.
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The present invention relates to a stacked steampath having both rotary and fixed components formed of wheels and rings respectively about a common axis. The present invention also relates to a dovetail bucket wheel for the stacked steam turbine.
Current integral cover reaction buckets are formed of large quantities of individual buckets that are assembled onto a machine rotor forging. Similarly, current nozzle stages are formed of large quantities of nozzles assembled onto a stator casing. The time and cost associated with rotor forgings and stator casings, rotor and stator machining, bucket and nozzle stock material, bucket and nozzle machining, and rotor and stator assembly add significantly to the costs to the steampath. Accordingly, there is a need to reduce the time and cost of manufacturing and assembling steampath hardware without impacting the integrity of the overall steam turbine design.
BRIEF DESCRIPTION OF THE INVENTIONIn a preferred embodiment of the present invention there is provided a steampath for a steam turbine comprising: a plurality of stacked wheels having a plurality of blades extending outwardly of the wheels and about a common axis; a plurality of stacked rings having a plurality of nozzles extending inwardly of the rings and about the common axis; the wheels and rings alternating along said axis forming respective stages of the steam turbine and defining the steampath.
In a further preferred embodiment of the present invention there is provided a steampath for a steam turbine comprising: a plurality of stacked wheels about a common axis with each wheel having a peripheral groove and a plurality of buckets each having a blade and a root, said root and said groove being shaped to retain the root of each bucket within the groove, and a plurality of rings mounting nozzles and alternating with the stacked wheels about the common axis defining with said buckets the steampath.
BRIEF DESCRIPTION OF THE DRAWINGS
Referring now to the drawings, particularly to
Alternating with the nozzle rings 12 are the rotor wheels 16 mounting the rotor buckets. For example, and in referring to
As illustrated, the steam path is built up to multiple stages by alternate placement of the stator rings 12 and rotor wheels 16 about a common axis. The various rings and wheels of the stationary and rotating components of the steampath are provided with hardware such that the rings and/or wheels cannot be assembled in the wrong location or direction or out of the predetermined order. For example, the stator rings 12 may have axial projections and recesses on adjacent axial faces which must align with one another to ensure that the adjacent rings correspond to successive stages of the steampath. Similarly, the wheels 16 may have projections and recesses to insure their accurate alignment in the predetermined order of the various stages.
Referring to
Similarly, and referring to
The studs which interconnect the stator rings 12 and the rotor wheels 16 need not necessarily extend the entire length of the steampath. The various stages may comprise sub-assemblies with each sub-assembly containing a predetermined number of stages. For example, six sub-assemblies of five stages per sub-assembly in a thirty stage steampath may be provided. The studs may extend only through the stages of each group or may terminate within the initial stator ring or wheel of an adjacent group to secure the sub-assemblies of stages to one another. A particular benefit of assembling the stator rings individually and rotor wheels individually facilitates the service and repair of the various stages. Moreover, the capacity to provide an individual stator ring or rotor wheel at each stage location, enables different materials to be used from location to location, i.e., from stage to stage. Thus, certain stages may use less costly materials without degradation of the overall integrity of the steampath. For example, the inlet stage of the steampath may be formed of material necessary to withstand the high temperature and pressure of steam at the steam inlet and which material may be costly. Subsequent stages, being exposed to lower temperatures and pressures may be formed of less costly material.
Referring to
Referring to
Referring to
While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
Claims
1. A steampath for a steam turbine comprising:
- a plurality of stacked wheels having a plurality of blades extending outwardly of the wheels and about a common axis;
- a plurality of stacked rings having a plurality of nozzles extending inwardly of the rings and about the common axis;
- the wheels and rings alternating along said axis forming respective stages of the steam turbine and defining the steampath.
2. A steampath according to claim 1, including a plurality of aligned openings through the wheels at spaced locations about the wheels and a plurality of studs extending through the openings to secure the wheels to one another.
3. A steampath according to claim 1, including a plurality of aligned openings through the rings at spaced locations about the rings and a plurality of studs extending through the openings through the rings to one another.
4. A steampath according to claim 1, wherein the blades and nozzles interdigitate with one another.
5. A steampath according to claim 1, wherein the blades are formed integrally with each wheel.
6. A steampath according to claim 1, wherein the wheels have a peripheral groove, a plurality of buckets each mounting a blade and a root, said groove being shaped to retain the root of each bucket within the groove.
7. A steampath according to claim 1, wherein the steampath includes a steam inlet end and a steam outlet end, the materials of the wheels forming stages at the inlet and outlet ends being different than one another.
8. A steampath according to claim 1, including a steam inlet end and a steam outlet end, the materials of the rings forming stages at the inlet and outlet ends being different than one another.
9. A steampath according to claim 1, wherein said rings in assembly form a stator for the steam turbine.
10. A steampath according to claim 1, wherein said rings are welded to one another to form a stator for the steam turbine.
11. A steampath according to claim 1, wherein said rings are welded to one another to form a rotor for the steam turbine.
12. A steampath for a steam turbine comprising:
- a plurality of stacked wheels about a common axis with each wheel having a peripheral groove and a plurality of buckets each having a blade and a root, said root and said groove being shaped to retain the root of each bucket within the groove, and a plurality of rings mounting nozzles and alternating with the stacked wheels about the common axis defining with said buckets the steampath.
13. A steampath according to claim 12, including a shear pin extending through margins of the groove and the root of a closure bucket to secure the closure bucket to the wheel.
14. A steampath according to claim 13, wherein said shear pin extends generally in an axial direction.
15. A steampath according to claim 13, wherein said shear pin extends at an angle canted to the common axis.
16. A steampath according to claim 12, including at least one grub screw for securing the closure and bucket and wheel to one another.
17. A steampath according to claim 12, wherein said plurality of rings form a stator for said turbine.
18. A steampath according to claim 12, wherein said plurality of rings are welded together to form a stator for said turbine.
19. A steampath according to claim 12, wherein said plurality of wheels are welded together to form a rotor for said turbine.
Type: Application
Filed: Aug 24, 2005
Publication Date: Mar 1, 2007
Patent Grant number: 7270512
Applicant: General Electric Company (Schenectady, NY)
Inventors: Christopher Sullivan (Ballston Spa, NY), Robert Bracken (Niskayuna, NY), Jeffrey Simkins (Rensselaer, NY), Stephen Swan (Clifton Park, NY), David Fitts (Ballston Spa, NY), Ronald Korzun (Clifton Park, NY), John Murphy (Niskayuna, NY)
Application Number: 11/209,624
International Classification: F01D 1/02 (20060101);